Apparatus for making a metal part

ABSTRACT

The invention relates to a facility for producing a metal component having at least two regions of different strength properties, said facility consisting of a heating unit ( 2 ) comprising heat-producing radiation sources ( 4 ) as well as a positioning device for at least one base body ( 1 ) consisting of metal, and a protecting device comprising at least one covering part for the contactless protection of a pre-determined surface region of the base body ( 1 ), the protecting device being arranged in the heating unit such that it remains therein during a temperature control of the base body ( 1 ) before the forming of the base body in a forming tool, the protecting part comprising a plurality of separately manipulatable covering parts ( 3   a,    3   b,    3   c,    3   d,    3   e ) which are respectively used to protect a predetermined surface region ( 1   a,    1   b,    1   c,    1   d,    1   e ) of the Base Body ( 1 ), and a Manipulator ( 5 ) is Provided for Each Covering Part ( 3   a  to  3   e ), by means of which the covering part ( 3   a  to  3   e ) can be moved, independently from the other covering parts ( 3   a  to  3   e ) in the heating unit ( 2 ), into a covering position in which it covers the pre-determined surface region ( 1   a  to  1   e ), or into an uncovering position in which it uncovers the pre-determined surface region ( 1   a  to  1   e ) for the irradiation of the radiation sources ( 4 ).

The invention relates to an apparatus for making a metal part having atleast two regions with different strength properties, comprising aheater with heat-generating radiation sources and with a positioner forat least one plate or similar base body made of metal, a shield with atleast one cover for contactless shielding of a predetermined region ofthe plate or the base body, where the shield is designed to remain inthe heater while the plate or the base body is heated and before it isformed in a deforming tool.

Such an apparatus is known from DE 10 2012 016 075.

The term metal part is to be understood as meaning both plates and flatproducts cut out of plates that form intermediate products for afinished part that will be manufactured from them. A method that is alsoused in the present invention is described in the prior art.Accordingly, a metallic base body, for example a steel sheet or a pieceof one, which can also be coated, is first heated to a suitabletemperature, for example, to austenitizing temperature in the case ofsteel. The coating can be, for example, an aluminum-silicon coating thatis alloyed by appropriate heating and thus creates an optimal connectionwith the base part. The base body or the plate is brought into theheater at this temperature, and is partially shielded by a shieldaccompanying the workpiece to prevent further heat penetration insubregions thereof, whereas the base body is still subjected to heat inthe corresponding heater. In this way, the unshielded region of the basebody or the plate continues to be kept at the austenitizing temperatureor the corresponding temperature, while the shielded region can cooldown in a controlled manner, for example below the austenitizingtemperature but above the martensite starting temperature. In this partregion preferably an average cooling rate prevails that is below thatcritical for martensite formation, such that the structure of thisregion after the subsequent forming, assuming the object is steel,mainly consists of ferrite and pearlite, regardless of the subsequentcooling rate during the forming process. The shielded regions cool downmore slowly than a passive cooling in air. After the shielding has beenremoved, the base body or the plate that has been accordingly processedand that then has a graded temperature profile obtained by the shieldingundergoes a shaping process using a tool, in particular, hot shapingwith press hardening at the same time. At least in the previouslyunshielded region of the base body or the plate, a cooling rate abovethe cooling rate critical for martensite formation (in the case ofsteel) is maintained. This means that the base body cools down soquickly that a predominantly martensite structure is created in thepreviously unshielded region. During the forming process, it is notnecessary to establish different cooling rates for the differentregions. In particular, the two regions of the base body can be cooleddown at a cooling rate greater than the critical cooling rate for theformation of martensite, since, due to the partial cooling of theshielded region that has already taken place, martensite conversion canonly occur in the region that was not previously shielded.

A corresponding shield is described in the prior art to carry out thismethod that is designed and used to cover a corresponding region of themetal part.

In principle, such an apparatus is well suited to produce customproducts. However, the conventional technology only allows creatingparts that have regions with two different strengths. If, in the finalstate, parts need to have more than two different strengths, this isconventionally only possible by prefabricating several parts that arethen joined to form a complete part, for example by welding.

Proceeding from this prior art, the object of the invention is toprovide an apparatus in the described type with which it is possible tocreate complex parts with different strengths that can be formed in onepiece.

To attain this object, the invention proposes that the shield comprisesa plurality of individually manipulable covers, each intended forshielding a predetermined surface region of the plate or the base body,and that a respective manipulator is provided for moving each cover inthe heater independently of the other covers into a covering position inwhich it covers the respective surface region, or into an exposingposition in which it exposes the respective surface region to theradiation from the radiation sources.

According to the invention, several separately manipulable covers areprovided, each of which is intended to shield a predetermined surfaceregion of the plate or the base body. For example, five such separatelymanipulable covers can be provided. Each cover has a respective suchmanipulator that can move the respective cover in the heaterindependently of the other covers into a covering position in which itcovers the predetermined surface region, or into an exposing position inwhich it exposes the predetermined surface region for the radiation fromthe radiation sources. This configuration makes it possible to create apart or a base body that has several, for example five, differentstrengths in a part that one single piece. The different strengths can,for example, improve the crash properties required in automobileconstruction and meet special requirements in this regard, even whileonly requiring a single, one-piece part. As is known in the prior art,this part undergoes a hot-shaping process after the correspondingheating or cooling, and a correspondingly rapid cooling can take placesimultaneously or with a time delay for press hardening.

It is particularly preferred that the manipulators are actuated by anelectronic controller installed on the apparatus or integrated with itto set the different operating positions.

The various covers can be moved, for example by mechanical drives, intothe covering positions or into the exposing positions, and themanipulators used for this purpose are actuated by an electroniccontroller. This makes it possible to store a corresponding programmingin the controller in order to set the manipulators into the desiredoperating positions in a suitable manner at different times.

It is also preferably provided that the manipulators are combined with atime controller so that they move the covers to the different operatingpositions as a function of time.

As a result, the manipulators can be combined with a time controllerthat can be adjusted by the operator so it is possible to position thecovers as a function of time, which in turn leads in a simple manner toa part that acquires a plurality of different strengths corresponding tothe arrangement of the plurality of covers.

It is also preferably provided that each cover consists of a pair ofcover templates lying opposite each other that cover a subregion of theplate or of the base body in the covering position, namely on theunderside, on the top, and optionally on the edge.

Such an arrangement enables a largely symmetrical arrangement of thepairs of individual cover templates forming a cover that can then beaccommodated in a simple manner in the heater. The heater can be afeed-through oven or a stationary oven.

In the covering position, the cover templates of each pair move towardeach other in such a manner that they form a continuous cover whereas inthe exposing position the cover templates are moved in the oppositedirection, such that they are next to the corresponding workpiece (plateor base body) on each respective side.

For this purpose, it is particularly preferably provided that themanipulators move each pair of cover templates of the cover into thedifferent operating positions at the same time.

It can also be provided that the covers of the apparatus that arearranged next to each other are arranged to form a movement gap.

It is preferably provided that the covers arranged next to each otherare spaced apart by a gap of 25 to 100 mm.

Such a configuration enables transition regions of a corresponding size,for example between 25 and 100 mm, such that the regions of differentstrengths do not directly adjoin each other, but rather via a transitionregion. This is often desirable for properties of the finished part thatare desired subsequently.

It can also be provided that the side edges of the covers or at leastsome covers have a greater material thickness than in the remainingregion of the covers and/or have a greater vertical distance from theplate or the base body in the covering positions.

Such a configuration enables influencing the transition region byvarying the thickness of the respective cover near its side edge that isadjacent the next element, such that the shielding effect is variable inthe direction of the transition zones to be formed. Such variability canalso be produced by the corresponding cover having a greater spacingnear its edge region from the plate or the base body in the coveringposition. For example, the cover can have an bent-up edge region. Bothmeasures can also be used at the same time.

In particular, it is preferably provided that a shaping tool isconnected to the apparatus or is arranged adjacent it for receiving andforming the plate or the base body after the heating, and optionallyhardening it.

The invention further provides a metal part in the form of a plate or aone-piece base body that is characterized in that the metal part hasmore than two surface regions of different strengths over its lengthand/or width.

Such a one-piece metal part is particularly advantageous in automotiveengineering because it can be adapted in a suitable manner to desiredcrash properties, and the transition regions between the heat-treatedregions can also be implemented differently. In particular, such a metalpart comprises a plurality of regions of different strengths, preferablythree to five such regions.

An embodiment of the invention is shown in the drawing and described inmore detail below, where:

FIG. 1 schematically shows a flat part having five regions of differentstrength;

FIG. 2 is a schematic representation of an apparatus according to theinvention.

FIG. 1 shows a metal part according to the invention in the form of aone-piece base body 1. This metal part has a plurality of regions 1 a, 1b, 1 c, 1 d, 1 e of different strengths over its length (seen in thedirection from left to right in the drawing). The different strengthsare indicated in the drawing by different hatchings. Although the metalpart in the form of the base body 1 is shown as a flat element, thisspecial feature is of course substantially achieved and realized evenwhen the base body 1 is hot formed and assumes a correspondingthree-dimensional shape.

FIG. 2 shows an apparatus with which such a metal part can beprefabricated before it is then formed and hardened in a deforming tool.

The apparatus is used to produce a corresponding metal part in the formof a plate or a base body 1 made of metal. The apparatus consists of aheater 2 with heat-generating radiation sources 4. The heater 2 can beimplemented as a feed oven or as a closed oven.

Positioners for the base body 1, on which the base body 1 can be placed,are provided in the heater 2, but are nevertheless accessible on allsides for radiant heat. These can be, for example, pin-like supports orthe like. Furthermore, a series of shields with covers 3 a, 3 b, 3 c, 3d, 3 e is provided. These are provided for contactless shielding of apredetermined surface region of the base body 1. These shields aredesigned to stay in the heater 2 during heating of the base body 1 inthe heater, prior to the base body being formed in a subsequent formingprocess and deforming tool.

According to the invention, the shield consists of a plurality ofseparately manipulable covers 3 a, 3 b, 3 c, 3 d, 3 e, each of which isintended for shielding a respective surface region 1 a, 1 b, 1 c, 1 d, 1e of the base body 1. Each cover 3 a to 3 e has a respective manipulator5 shown here in the drawing by arrows that at the same time illustratethe movement of the respective cover 3 a to 3 e. This configurationmakes it possible to move each of the covers 3 a to 3 e independently ofthe other covers in the heater 2 into a covering position, in which itcovers the predetermined surface region 1 a to 1 e, or into an exposingposition as shown in the drawing, in which it exposes the predeterminedsurface region to the rays of the radiation sources 4.

The manipulators 5 can be actuated by an electronic controller 6 thathard-wired or wirelessly connected to the manipulators 5. The controller6 is mounted on apparatus parts, for example on a control panel of theheater 2.

In particular, the manipulators 5 can be combined with a time controllervia the controller 6 such that they can move the covers 3 a to 3 e intothe different operating positions as a function of time.

Each cover 3 a to 3 e consists of a pair of cover templates positionedopposite each other, as can be clearly seen in FIG. 2, each of which cancover a subregion of the base body 1 in the covering position,specifically on the underside, top, and optionally on the edge. In thedrawing, the cover templates of each cover 3 a to 3 e are shown in theexposing position. In the covering position, the covering templates aremoved toward each other corresponding to the direction indicated by thearrows, such that they completely cover the corresponding region of thebase body 1. The manipulators 5 preferably move each pair of covertemplates of each cover 3 a to 3 e simultaneously into the differentoperating positions.

The covers 3 a to 3 e of the apparatus are next to each other andpreferably arranged to form at least one movement gap, and arepreferably arranged to form a spacing gap from each other of 25 mm to100 mm. In this way, corresponding transition zones can be formedbetween the individual surface regions 1 a to 1 e.

The apparatus is completed by a deforming tool that is not shown in thedrawing. After being heated as intended, the base body is fed to thedeforming tool, shaped in it, and optionally press-hardened at the sametime.

With the apparatus according to the invention, it is possible in asimple manner to make parts having several different strengths in aone-piece part, this being achieved by correspondingly controlling thecovers that are moved in the heat treatment system 2 at different times(in the direction indicated by the arrows) to set the differentoperating positions. As a result, each controlled region of the basebody 1 can reach a different heat treatment temperature and subsequentlya different heat-treatment temperature in the further course of themethod, which leads to different strengths in the one-piece finishedpart.

The invention is not limited to the illustrated embodiment, but ratheris variable in many ways within the scope of the disclosure.

All new individual and combination features disclosed in the descriptionand/or drawing are regarded as essential to the invention.

1. An apparatus for making a metal part having a a plurality ofdifferent strength properties, the apparatus comprising: a heater havingheat-generating radiation sources, a positioner for a heat-treatableworkpiece made of metal, a shield having a plurality of covers forcontactless shielding of a respective surface regions d of theworkpiece, and constructed to remain in the heater during heating of theworkpiece before same is shaped in a deforming tool, and a respectivemanipulator for moving each cover in the heater independently of theother covers into a covering position in which it covers the respectivesurface region or into an exposing position in which it exposes therespective surface region to rays of the radiation sources.
 2. Theapparatus according to claim 1, further comprising: an electroniccontrolling operating the manipulators and installed on the apparatus orintegrated in it for setting the different operating positions.
 3. Theapparatus according to claim 1, further comprising: a time controllerfor operating the manipulators to move the covers into differentoperating positions as a function of time.
 4. The apparatus according toclaim 1, wherein each cover consists of a pair of opposing covertemplates that together cover the respective region of the workpiece inthe covering position.
 5. The apparatus according to claim 4, whereinthe manipulators move each pair of cover templates of the coversimultaneously into the different operating positions.
 6. The apparatusaccording to claim 1, wherein the covers are spaced from one another andform movement gaps.
 7. The apparatus according to claim 6, wherein eachof the covers is spaced from adjacent covers by a gap of 25 to 100 mm.8. The apparatus according to claim 1, wherein side edges of at leastsome of the covers have a greater material thickness than the rest ofthe respective covers or have a greater vertical spacing from theworkpiece in the covering position.
 9. The apparatus according claim 1,wherein the deforming tool is connected to the apparatus or is arrangedadjacent it, and receives and shapes the workpiece after heating.
 10. Ametal part in the form of a plate or a one-piece base body, wherein themetal part has more than two surface regions of mutually differentstrengths over its length and/or width extension.